1. Field of the Invention
The present invention relates to a method and to an apparatus suitable for carrying out this method for producing multi-layered confectionery by means of several applicators arranged along a conveyor system.
2. The Prior Art
The most frequently used applicators are extruders, but occasionally, particularly towards the end of the production line, placing devices, such as nut or cherry depositing devices, are also used. The conveyor system is usually constructed as a conveyor belt, or as a conveyor screen, which runs below the applicators. The first applicator produces rows of a first layer, i.e., the "base plates" as it were, of the confectionery to be produced, running at right angles to the conveyor direction. These "base plates" are moved by the conveyor system below a second applicator where the second confectionery layer is applied, and so on until the confectionery is made up of the desired number of layers.
The difficult with this type of confectionery production system is in bringing the individual confectionery layers together so that they are exactly aligned with one another. If this does not happen, then unpleasant looking, crooked or misshapen products are the result. The principal reason for this difficulty is the inaccuracy in the transporting by the conveyor system. This conveyor is constructed as a belt or screen and has a tendency both to shift transversely with respect to the direction of movement and, due to uncontrolled stretching and slippage in the drive mechanism, to fluctuate in its direction of movement. Attempts were made initially to overcome this difficulty by arranging the applicators so that they are moveable relative to the transport system. It was the responsibility of the operating staff to monitor the apparatus continuously. As soon as a crooked or misshaped appearance was observed in the confectionery, it became necessary for the staff to correct the position of the applicators in relation to the displacement of the transport system.
In addition to the high expenditure of energy involved, this attempted solution also had the disadvantage that a correction can only be made after the error has already become visible to the staff; i.e., when the quality of the products has already visibly deteriorated. Therefore, there has been no shortage of attempts to replace, or at least to relieve, the operator by mechanical means at this point. In this case, considerations have concentrated on keeping the conveyor system running straight.
A prior art device is known which detects the straight running of a transport system constructed as a conveyor belt by using a sensor pin which rests against one of the side edges of the belt. This sensor pin acts on a switch which then emits switch pulses when the conveyor belt shifts unacceptably far to the right or to the left. The switch pulses are transmitted to a control arrangement which steers the belt in the opposite direction in order to achieve an acceptable straight line movement for the conveyor belt.
A similar solution is known from DE-OS 3,711,916. In that publication, it is proposed to provide a marking, for instance, in the form of a continuous thread, a coating of varnish or the like, on the surface of the conveyor belt. This marking is scanned by means of sensors which are arranged to the right and left of the marking and act without contacting the marking. Here too the sensors produce control pulses which, in turn, seek to achieve a straight line movement for the conveyor belt by steering it in the reverse direction opposite to its direction from the straight line movement.
It is common to both prior art systems that the lateral deflection of the conveyor belt can only be fully corrected in the region of the sensors. Deviations during the travel movement of the conveyor belt before the sensor, or between the sensor and a guide roller which steers the belt in the opposite direction, are not recognized. Thus, these deviations are not corrected in these prior art systems. Furthermore, displacements caused by slippage, or stretching, of the conveyor belt are also not eliminated. Thus, it is still the responsibility of the operating staff to monitor the apparatus continuously for accuracy in the formation of the confectionery layer and to intervene occasionally so as to correct any misalignment in the layer formation when necessary. Correction is by adjusting the position of the applicators. In the case of displacements of the conveyor belt in the direction of belt travel, correction is also by altering the application time interval of the applicators.